British & Irish Lions boss Warren Gatland claimed earlier this month that he has already picked his captain, but the weekend's Heineken Cup action may have prompted him to change his mind. This week's Scrum Sevens assess the contenders and offers a run-down of their qualities ahead of the squad announcement - and skipper - on April 30.

Leadership: O'Connell has been Munster's figurehead for the past few seasons and also led the Lions in 2009. He is Ireland's equivalent of Martin Johnson and there can be no doubts over the inspirational presence he offers.

Fear factor: The site of the red-headed giant in full flight would be enough to scare most players, and from a Lions point of view, hopefully those wearing green and gold will be quaking in their boots. He may have lost the odd yard of pace, but his impact is still ferocious.

Form: He has barely played any rugby over the past nine or so months and last pulled on an Ireland shirt over a year ago. But since returning from the back surgery he underwent in January, O'Connell has picked up two Man of the Match awards and was the star performer in Sunday's Heineken Cup quarter-final victory over Harlequins.

Lions pedigree: O'Connell toured in 2009 as captain and started all three games against the Springboks. He was also part of the 2005 tour to New Zealand and earned three Test caps against the Kiwis as the tourists got 'blackwashed'.

Odds: After Sunday's showing against Harlequins, O'Connell is now favourite with the bookies at 10/11.

Leadership: The openside led Wales into the 2011 Rugby World Cup and carried out the role admirably but recently he has seen his captaincy credentials wane. Wales plumped for Ryan Jones over Warburton for three of their five games during the 2013 Six Nations while for their final clash against England, Warburton passed up the captaincy with Gethin Jenkins receiving the honour.

Fear Factor: His physical presence may not strike fear into the opposition, but his ability is enough to cause the Wallabies some sleepless nights.

Form: His form for the bulk of the 2012-13 campaign has been ordinary by his high standards but he worked perfectly in tandem with Justin Tipuric in Wales' Six Nations-clinching win over England.

Lions pedigree: He is yet to tour with the Lions but should be in the mix come the summer.

Odds: Warburton's odds shift around like the British weather and was at one stage 36/1 to lead the Lions - he is currently second favourite at 10/3.

Leadership: The Ospreys' captain is a hugely passionate figure and ex-Lions skipper Johnson has tipped the lock as a potential leader come the summer. Johnson said: "He's played a lot of games, he's done it, he has been out there before with the Lions in '09, so I think he's in the frame."

Fear Factor: Some perceive him to lack the required bulk to take on the world's best, but he frequently makes a mockery of these assertions. He carries with ferocity and has the tactical brain to upset most team's lineouts.

Form: He was immense against England and despite missing the first part of 2013 due to injury, he is showing no ill-effects. He has performed well on the domestic scene for the Ospreys and Gatland, due to his Wales role, will be fully aware of the lock's qualities.

Lions pedigree: Jones started the first Test against the Springboks in 2009 but missed the second with the coaching staff preferring Simon Shaw. He finished the tour with three caps having come off the bench in the second and third Tests.

Leadership: One of the sport's finest ever players, O'Driscoll has skippered Ireland, Leinster and the Lions. Former Ireland boss Declan Kidney plumped for Jamie Heaslip as Ireland captain during the past Six Nations, a decision which provoked public outcry, but the centre still led frequently from the front.

Fear factor: He never shirks a challenge and can rip defences apart with ball in hand. Regardless of which team he is playing for, he is frequently earmarked as their main threat and still puts teams to the sword on both the domestic and international scene.

Form: In the first match of this season's Six Nations, O'Driscoll was imperious. He has barely played for Leinster this season - making just eight starts - but he still has the ability to shine on whatever stage he is playing.

Lions pedigree: When he finally hangs up his boots, he will go into the Lions' pantheon as one of their greatest players. He terrorised the Wallabies in 2001 but his tour in 2005 was cut short when he was on the wrong end of a spear tackle. Come 2009 he started the first two Tests against the Boks but missed the third due to injury.

Odds: He is in the mix to captain the Lions this time around and is ranked at 6/1 to be handed the honour.

Leadership: The hooker has captained Ireland and Ulster in the past and is always a vocal presence on the field. Former Lion and compatriot Stephen Ferris summed up Best's leadership qualities perfectly, saying: "He just says what everyone needs to hear. He doesn't say an awful lot but what he does sinks in. When he needed to say something he did; if nothing needed to be said he just got on with his job."

Fear factor: He may not have the same physical frame as your O'Connells, but he is a shrewd operator and opposition lineouts know that they will have to be at their best if they are to snuffle any ball.

Form: Best came out of the Six Nations alongside Wales' Richard Hibbard as one of the two in-form hookers available to Gatland. He performed well throughout Ulster's Heineken Cup campaign and is a genuine contender to start in their first Test against the Wallabies.

Lions pedigree: He has never toured with the Lions but has played in two World Cups and at the highest level on the domestic scene.

Leadership: He is the focal point of both Conor O'Shea's Harlequins set-up and England's recent resurgence under Stuart Lancaster. He ended the 2011-12 campaign lifting the Premiership trophy at Twickenham and could do the same come May. He came in for criticism towards the end of the autumn Tests but answered those who questioned him with a barnstorming display against the Kiwis a week later.

Fear factor: While he may not be the most vocal of skippers, he has an incredible effect on the rest of his team, where his presence seems to spur them on to up their game.

Form: Robshaw's had another impressive campaign for Quins. While he may not have hit the heights of last season, he should still travel with the Lions. His versatility - with the ability to play across the back-row - will also act in his favour.

Lions pedigree: Robshaw has never really been on the Lions' radar but he now has plenty of Test experience.

Odds: Robshaw has previously been favourite but he has now drifted to 14/1.

Leadership: He led Wales to their second Six Nations championship in as many years when he was named skipper for their title shootout with England. He helped inspire the men in red to the biggest ever victory over their cross-Severn foes.

Fear factor: On his day, Jenkins is one of the world's outstanding loose-head props. If he is ever having a bad day in the scrum then he usually makes up for this by tearing up in the loose with a performance packed with power and agility.

Form: While the Top 14 has been an attractive proposition to many of Jenkins' Wales team-mates, he never really made Toulon home. He barely played in the opening few months of the season and found himself behind Andrew Sheridan in the pecking order. But throughout the Six Nations he was performing up to his normal high standard and at the moment, looks to be vying with Cian Healy for the starting Lions berth.

Lions pedigree: He started all three Lions Tests in 2005 and backed that up with two more caps in 2009. He knows what it takes to be a Lion and this may put him in good stead come June.

Odds: Jenkins is considered as an outsider for the Lions captaincy and you can find odds of around 20-25/1 if you think he might receive the honour.